The prior art includes a variety of types of material spreaders. Conventional lawn fertilizer spreaders include a hopper and a finger agitator rotated by spreader wheels. More closely related to the invention apparatus are material spreaders adapted for use in conjunction with the spreading of rock or other relatively hard and relatively large size particulate material. A number of companies make material spreaders for evenly spreading a layer of topping material on the wet surface of spans of concrete. The conventional spreader mounts one or more hoppers on a bridge which spans the width of the concrete. The hoppers are driven back and forth on the bridge to spread the material. The bridge is mounted on wheels and is manually moved lengthwise of the span after each pass of the hoppers. The hopper drive mechanism for a spreader of this type is typically powered either electrically or pneumatically which requires either power cables or air lines to be fed back and forth across the concrete span being worked. Such arrangements inherently require additional support structure and expense for the added structure, cables and air lines. U.S. Pat. No. 4,349,294 describes one such spreader. Trade literature distributed by K & G Equipment Design, Inc., of Yankton, S.D., describes the "K & G" material spreader, another such spreader. Also, U.S. Pat. No. 4,411,554 describes a spreader having an electric drive and two spaced-apart hoppers on a bridge. In applicant's copending application, Ser. No. 593,108, filed Mar. 26, 1984, entitled "Hydraulically-Powered Material Spreader", there is described a substantially improved material spreader in which the hoppers and spreader box are mounted on a support structure which is driven back and forth along an elevated path by means of gasoline engine powered hydraulic apparatus also mounted on the same support structure. Heat, which accumulates in the hydraulic fluid during operation of the spreader, is dissipated by means of an improved reservoir/hopper-cooling arrangement which allows the heat to be absorbed both by a hopper wall and by the material being spread which significantly contributes to making such system practical.
Experience with the type hydraulically-driven spreader described in applicant's copending application has proven that such spreader is well suited to spreading relatively uniform and relatively small size particles such as sand. However, the spreader taught in applicant's copending application as well as all other spreaders known to applicant have failed to provide a spreader uniquely adapted for spreading large size rock and particularly with a hydraulic drive.
A demand for spreading relatively large and non-uniform size rock, for example of 1/2" to 2" screen size, has arisen because of the trend toward using exposed aggregate in buildings and also because of the trend in forming patios, sidewalks, and floors with relatively large rock surfaces. Rock surfaces provide an aesthetically attractive appearance and when used as a floor surface can substantially increase the wear life when the rock being spread is chosen to be of an extremely hard type.
The object of the present invention thus becomes that of improving upon applicant's spreader as described in applicant's copending application, Ser. No. 593,108, with regard to providing a spreader more specifically adapted and useful in spreading relatively large and relatively non-uniform rock. This and other objects will become apparent as the description proceeds.